Regions
Vancouver Island.
Cornice fall and wet loose avalanches on steep/rocky and unsupported terrain observed at Alpine elevation band.
Past Weather
Warm double digit air temperatures continue to melt surface snow, destabilize upper snowpack layers and weaken cornices.
Weather Forecast
Freezing levels will continue to drop over the next several days. Below freezing air temperatures expected by Friday at Mid mountain elevation band across Vancouver Island. Wednesday: No new precipitation, Winds light from the NW (moderate NW gusts in afternoon for North and Central Island), Freezing level 2,300 meters Temps at 1500 meters up to +8 degrees.Thursday: No new precipitation, Winds light from the North, Freezing level 1,750 meters. Temps at 1500 meters up to + 3 degrees.Friday: Less than 5cm Snow/5mm Rain (depending on elevation) expected in late afternoon, Winds light from the South, Freezing level 1,400 meters. Temps at 1500 meters -1 degrees.
Terrain Advice
Please respect the current closures at Mount Washington, no access is permitted at anytime on the ski areas slopes or terrain.During periods of intense warming and sunshine, avoid solar facing terrain.Avoid travelling both above and below cornices.Early starts may help to ensure you can accomplish your trip objective prior to arrival of day time high’s when the snowpack will become increasingly more unstable.Major concern remains with the fact that no below freezing temperatures are taking place on Vancouver Island’s mountain ranges overnight. Expect continued destabilization within the layers that exist within the upper snowpack. On Friday air temps will cool and help consolidate melting snow problems. Possibility of isothermal snow may make for extremely challenging and dangerous travel as snow may readily collapse under an individual’s weight.
Snowpack Summary
Melting (isothermal snow) exists within the upper 10cm of the snowpack. A series of layers exists within the upper snowpack that are weakened as a result of the consistent above zero air temperatures. Snow is retaining below zero degree composition down 50cm from the surface of the snowpack where an intact ice layer remains frozen and reactive (stubborn/hard range) to testing.
Snowpack Details
- Surface: 5-10cm of isothermal melting snow.
- Upper: Down 30cm from the surface, a wet (water/snow) interface, upper snowpack is dense and supportive.
- Mid: Well settled and dense. Contains a series of ice layers (still fully frozen/below zero degrees) reactive to testing
- Lower: well settled and dense
Confidence
Moderate - On Friday, below zero degrees air temperatures will return to Vancouver Island mountain ranges. Solar Aspects remain primary concern with day time heating. Avalanche ratings reflect the highest danger level expected over the course of the day.
Problems
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.
Wet Slabs
Wet Slab avalanches are the release of a cohesive layer of snow (a slab) that is generally moist or wet when the flow of liquid water weakens the bond between the slab and the surface below (snow or ground). They often occur during prolonged warming events and/or rain-on-snow events. Wet Slabs can be very unpredictable and destructive.